Mounting for light sensitive devices



Dec. 14, 1937. E. Ross MOUNTING FOR LIGHT SENSITIVE DEVICES Filed Jun 8 PIE. 1-

ATTORNEY Patented Dec. 14, 1937 I g UNITED STATES PATENT MOUNTING FOR LIGHT SENSITIVE DEVICES Application June 8,

14 Claims.

This invention relates to sound reproducing apparatus and has particular reference to a mounting for a light sensitive element to be used there- In sound reproducing apparatus such as that employed in conjunction with motion picture apparatus to translate a beam of light, as modulated by a sound record on a motion picture film, into corresponding electrical current impulses, it is often necessary, due to the particular construction of the film gate, sprockets and other ancillary film moving mechanism as well as the usual compact form of the sound head, to locate the light sensitive cell or other electro-optical translating device in an inaccessible position. Light sensitive cells require occasional removal for cleaning or replacement due to deterioration and wear, which replacement, when necessitated during reproduction, must be accomplished as quickly as possible.

One object of the present invention is to facilitate the positioning and interchanging of a light sensitive unit, particularly a photoelectric cell, in a sound reproducing apparatus.

This is accomplished by providing within a casing which houses the sound translating mechanism, a bracket pivotally supported at one end and adapted to support at its other end a light sensitive element, such as a caesium or potassium photo-electric cell, in operative relation to a beam of light modulated by a sound record on a film passing through the casing. The bracket is adapted to swing the light sensitive cell, normally lying in a substantially inaccessible position when in operative relation with the modulated light beam, to a position adjacent an opening in the casirg whereby the cell may become readily accessible. Preferably means such as a spring pressed detent are providedto lock the bracket and cell in normal operative position.

Another object of the invention is to protect a light sensitive unit from electrostatic charges in any operative position thereof. This is accomplished by forming the pivotal bracket of an electrostatic shielding material, such as aluminum, and by providing a longitudinal passage therethrough to carry the conductors for the light sensitive cell. These conductors are passed both through the bracket passage and an opening in the pivotal connection co-extensive with the passage. Preferably an electrostatic shield is also placed over the light sensitive cell with an opening therein to allow the modulated light beam to be received by the cell.

In sound reproducing apparatus it may be de- 1936, Serial No. 84,111

sirable at times, to test the light sensitive cell and its circuit, including amplifiers, loudspeakers, etc., by impressing upon the cell a beam of light, other than the usual exciter lamp, from the exterior of the apparatus casing. The present invention, through its particular light cell support and its electrostatic shielding, allows the cell to be tested from the exterior of the casing while retaining the same electrostatic shielding therefor as whenthe cell is in operative relation with the normal modulated light beam within the cas- More particularly describing the invention, reference is had to the accompanying drawing wherein:

Fig. 1 is an elevational view, with parts broken away, of a sound reproducing head such as employed in motion picture projectors and embodying the present invention.

Fig. 2 is a plan sectional view of the photoelectric cell mount and is taken along the line 22 of Fig. 1.

Fig. 3 is an exploded view of the pivotal connection for the cell mount.

Fig. 4 is a sectional view of the pivotal connection taken along the line 4-4 of Fig. 2.

The sound reproducing apparatus is shown as comprising a casing II (Figs. 1 and 2) adapted to be secured in any suitable manner (not shown) to a-motion picture projector and which has an opening I 2 extending in a vertical plane along one side thereof. A cover door I3 is hingedly supported at M on the right hand end of the casing I I to allow for threading of the film, cleaning and replacement of parts when opened. The optical system for the sound apparatus includes an exciter lamp I5 and a lens tube I6. The tube I6 is provided with a suitable slit and lens assembly to focus a beam of light from the lamp I5 upon the sound track portion of film I! as it passes through the casing II either from a motion picture projector mechanism thereabove or directly from a supply reel (not shown). The light beam emerging from the tube I6 is in the form of a fine horizontal slit of light which is focused upon the film I! at a point IS.

The film II passes downwardly through a slot 28 formed in the upper wall of easing H and is guided between a pair of idler rollers and 22, and around a third edge guide roller 23. From roller 23 the film passes between an inertia controlled film driven roller, shown by dotted lines 24, and a presser roller 25 mounted on the upper portion of a sound gate member 26. The film is then guided between an aperture plate 21 and suitable spring presser shoes 28 on sound gate 26, past the sound translation point l9, thence around a constant speed film driving sprocket 29 and a hold-back sprocket 30. The film on leaving sprocket 30 is guided on to a suitable take-up reel below the casing H (not shown). The sound gate 26 is pivotally supported at its upper end for movement about a horizontal axis by a suitable pin 3| and is held in operative relation with the aperture plate 21 by means of a latch member 32 and has rotatably supported at its lower end a pad roller 36 adapted to hold the film I1 in engagement with the sprocket 29. Latch member 32 is pivotally supported at 33 upon a sound gate bracket I8, and is held in engagement with the lower end of sound gate 23 by means of a tension spring 34. On moving the outer end of the latch member 32 downwardly against the action of the spring 34, the lower end of the sound gate 26 may be swung in a clockwise direction to engage a notch 35 on the upper surface of latch 32, thus opening the sound gate and allowing threading of the film therethrough. This portion of the sound head is more fully disclosed in copending application S. N. 48,278 filed Nov. 5, 1935, and certain features claimed therein.

An electrostatically shielded partition 31 in the upper right hand corner of the casing H has a lower wall section 31' to which is pivotally connected at 38 one end of a photoelectric cell brack- An enlarged opening 40 formed in the opposite end of the bracket 39 has a counterbored seat 41 therein adapted to receive a photocell socket 42. An enclosure cap 43 is provided in a counterbored section of the opening 40 adjacent the exterior of the casing II and has secured to the central portion thereof, an inwardly extending stud 44. A screw 45 is provided to secure the socket 42 and the cap 43 in place. A photoelectric cell as of the caesium or potassium type, shown by the dot and dash lines 46, has a base thereon suitable for engagement in the socket 42. A tubular light shield 41 enclosing the envelope of cell 46 is frictionally supported'by engagement with the sides of the opening 49 and has an opening 43 therein to admit the sound modulated light beam passing from film E1 to the cell 45 when in its normal operative position. The shield 41 is formed of metal to shield the cell 46 from any stray light rays other than the sound modulated light beam and also to shield the cell from any extraneous static charges built up by the moving film, etc.

As shown in Figs. 2 to 4, inclusive, a passage 39 is provided, extending longitudinally within the bracket 39, and communicates with a vertically extending opening 59 in a bushing member 51. Member 51 is preferably pressed into a hole formed in the bracket 39 and is journaled in a bearing formed by a hole provided in the lower wall section 31', thus forming the pivotal connectionior the bracket 39. It will be noted that the axis of the bushing member forming the axis of the pivotal connection 38, is substantial-- ly in line with the opening 48 in the cell shield 31 and the path of the modulated light beam reaching the cell 43. Thus the cell 46 may be placed in close relationship with the aperture plate 21 and at the same time allowing it to be swung away from the plate 21 without striking.

The forward portion of bracket 39, containing the cell socket 42, extends outward into an offset or indentation portion I3 fomied on the door 13. The particular relation of the bracket 33 and its pivotal connection 38 with the opening l2 thus necessitates only a relatively small angular movement of bracket 39 to carry the cell 46 into the opening :2.

A pair of conductors 52 are attached to the socket 42 and extend through the passage 49 in bracket 39 and upwardly through the opening 50 inbushing 5!, into the partition 31. The bracket 39, cap 43, and wall section 31' are formed of metal or other material suitable for v shielding electrostatic charges from the conductors 52 and the photoelectric cell 45. A photoelectric cell transformer may be provided in the partition 31 to connect the conductors 52 to suitable amplifiers (not shown).

From the above construction it will be seen that the cell 46 may be swung by means of the bracket 39 into a position shown by the dotted lines 53 -(Fig. 2) to allow the cell to be readily removed from or replaced in its socket 42. It will also be seen that, on swinging the bracket 39 into the position shown by the dotted lines 53, the photoelectric cell 46 will remain in operative relation with the conductors 52 and its associated circuits so as to allow for testing of the photoelectric cell and its circuits. Furthermore, the electrostatic shielding qualities of the cell mount are retained in all positions of the bracket 39, thus allowing the same operating conditions to obtain in any position.

The end portion of the bracket 39 adjacent the pivotal connection 38 has a pair of arcuate slots 54 and 55 therein concentric with the bushing 5|. A pair of shoulder screws 56 and 51, engaging washers 53 and 59, respectively, are passed through the slots 54 and 55, respectively, and are threadably secured within holes 60 and 6|, respectively, provided in the lower wall 31 of partition 31. A U-shaped spring 62, having holes 65 and 66 to receive the screws 56 and 51, respectively, is interposed between the washers 58 and 59 and the bottom surface of the bracket 39. .This spring 52 has a detent 63 formed thereon which is adapted to engage a notch or groove 64 provided on the lower surface of the bracket 39. The groove 54 is so located that the detent 53 on spring 62 snaps thereinto when the bracket 39 is positioned to hold the cell 46 in its normal operating position to receive a modulated beam of light passing through the film 11. This locking action between the detent 63 and the groove 94 thus serves to hold the cell 43 in correct alignment.

I claim:

1. A light sensitive cell mount comprising a stationary support, a bracket having a passage therein, a socket on said bracket adapted to support a light sensitive cell, a pivotal connection between said bracket and said support, said connection having an opening along the pivotal axis thereof communicating with said passage, and current carrying conductors attached to said socket and extending through said passage and said opening in said pivotal connection.

2. A light sensitive cell mount in accordance with claim 1 wherein said support and said bracket form an electrostatic shield.

' 3. A light sensitive cell mount comprising a stationary support, a hollow bracket having an enlarged transverse opening at one end thereof communicating with the hollow portion, a pivotal connection between the opposite end of said bracket and said stationary support, said connection having an opening along the pivotal axis thereof communicating with said passage, a

socket in said enlarged opening adapted to support a light sensitive cell, current carrying conductors attached to said socket and passing through said passage and said opening in said pivotal connection, and a shield member covering said enlarged opening and having an aperture therein to allow light to be received by said cell, said shield member and said bracket being formed of electrostatic shielding material.

4. In a sound reproducing apparatus, a casing having an opening at one side thereof, means for projecting a beam of light in said casing, a bracket having one end thereof pivotally supported in said casing for movement about an axis substantially parallel to a line in the plane of said opening, means on the opposite end of said bracket for supporting a photoelectric cell in said casing in operative relation with said beam of light when said bracket isin one position, the. axis of said cell lying substantially normal to the plane of said opening when said bracket is in said position, said bracket being adapted 'to be swung around to allow the axis of said cell to assume a position substantially parallel to a line in the plane of said opening.

5. In a sound reproducing apparatus a casing having an opening at one side thereof, means for producing a beam of light in said casing, a bracket pivotally supported adjacent one end thereof in said casing for movement about a vertical axis and having a longitudinally extending passage therein, said passage communicating with a horizontally extending opening in the opposite end of said bracket, a socket in said bracket opening for supporting a photo-sensitive cell in operative relation with said beam of light when said bracket is in one position, said cell extending on the opposite side of said bracket from said opening, conductors extending through said passage and connected to said socket, a shield covering said opening in said bracket and having an aperture therein for admitting said beam of light to said cell when said bracket is in said position, said shield and said bracket forming an electrostatic shield for said cell and said conductors, said bracket being swingable toward said casing opening whereby said cell may be viewed directly through said shield aperture from the exterior of said casing opening.

6. In a sound reproducing apparatus, a casing having an opening at one side thereof, means for producing a beam of light in said casing, a bracket pivotally supported at one end thereof, means on the opposite end of said bracket for supporting a photo-sensitive cell in a substantially inaccessible position in said casing for receiving said beam of light, said bracket being swingable into said opening to render said cell accessible from the exterior of said opening.

7. A photo-sensitive cell mount comprising a wall section, a bracket having a passage extending therein, a pivotal connection between one end of said bracket and said wall, said pivotal connection having an opening therein communicating with said passage, said opening extending coaxially with the axis of said pivotal connection, said bracket having an opening at the opposite end thereof communicating with said passage, a socket in said opening adapted to receive a photo-sensitive cell, and conductors attached to said socket and extending through said passage and said opening in said pivotal connection.

8. In a sound reproduction system, the combination of a casing having an opening therein,

means for projecting a beam of light in'said casing, a bracket adapted to normally support a photo-sensitive cell in said casing in a position to receive said beam of light and means in said casing operatively connected to said bracket whereby said bracket may be moved to carry said cell into said opening.

9. In a sound reproduction optical system, the combination of a casing having an opening therein, means for projecting a beam of light in said casing, a bracket adapted to normally support a photo-sensitive cell in said casing to receive said beam of light, and pivotal supporting means for said bracket whereby said bracket may be moved to carry said cell intorsaid opening.

10. A sound reproduction system, comprising a casing having an opening therein, means for projecting a beam of light in said casing, a bracket, a socket at one end of said bracket for supporting a photo-sensitive device, means for pivotally supporting the opposite end of said bracket in said casing for normally supporting said cell in said casing to receive said beam of light, said bracket being movable to carry said cell into said opening.

11. In a sound reproduction system, the combination of a casing having an opening therein,

means for producing a beam of light in said casing, a photo-sensitive cell in said casing for receiving said beam of light, a bracket for said cell, a pivotal connection between said bracket and said casing whereby said cell may be swung into said opening to facilitate removal thereof and means for locking said support and said cell in operative relation with said beam of light.

12. The combination of a wall section, a bracket having a passage therein, a pivotal connection between one end of said bracket and said wall section, said pivotal connection having an opening therein communicating with said passage, a photo cell socket at the opposite end of said bracket, conductors electrically connected to said socket and extending through said passage and said opening, said bracket having an arcuate slot therein concentric with the axis of said pivotal connection, a spring, means extending through said slot for holding said spring in engagement with said bracket, said spring being adapted to snap into a notch in said bracket when said bracket is moved to a predetermined position.

13. In a sound reproducing apparatus a sound gate, a wall section, a bracket, a pivotal connection between one end of said bracket and said wall section for permitting movement of said bracket about a vertical axis, a photoelectric cell disposed horizontally on the opposite end of said bracket, said bracket being adapted in one position thereof to support said cell in operative relation adjacent said gate, means for locking said bracket in said position, said bracket being adapted to be moved to carry said cell away from said gate for replacement thereof.

14. A sound reproducing apparatus comprising a casing having an opening therein, a door covering said opening and having an indenture therein, a bracket, means for pivotally supporting said bracket at one end thereof in said casing, said bracket having means for sup-porting a vacuum tube device at the opposite end of said bracket, a

sound gate in said casing, said bracket being. 

